Mar 7, 2013 8:09 PM

I told the Norfolk Biodiversity Information Service about it but didn't get any help with identification.

It was around 2 and half feet long

Quite girthy (thicker than my wrist)

Run over by a boat

In the River Wensum in Norwich

It's too big to be a Brook Lamprey, and seemed a little too big to be a River Lamprey. I thought it looked most like a Sea Lamprey but i couldn't find any information about them living in the River Wensum.

Most probably a sea lamprey, which is back in good numbers in the River Tamar in south-west England, at least. And there're enough endangered species in the world without jokes/calls for extinction as there'll be at least one other idiot reading that statement and then going out to stamp on a lamprey's head. The fish is an indicator of good water quality, and although a parasite, it seldom kills its host.

I agree with mac, & the River Lamprey is distinguished from the Sea lamprey by having a uniform colour rather than the marblings & blotchings characteristic of the s.l. ; & the dorsal fins of sea lamprey distinctly separate, as it seems the 2nd photo shows.